Question

The length of a minute hand of a wall clock is $8.4cm$. Find the area swept by it in half an hour.

• A. $100c{m}^2$
• B. $110.88c{m}^2$
• C. $120c{m}^2$
• D. $130c{m}^2$

Answer 1

Answer: (B)

$110.88c{m}^2$

We know that minute hand covers ${180}^o$ in half an hour, which is a semicircle, hence area is

$\Rightarrow \frac{1}{2}\left(\pi \right)\left(r^2\right)=0.5\times 3.1428\times (8.4{)}^2=110.88c{m}^2$